Internal Fit of Single Crowns Produced by CAD/CAM and Lost-wax Metal Casting Technique Assessed by the Triple-scan Protocol

Abstract

ObjectivesTo digitally study the internal fit of single crown fixed dental prostheses produced by CAD/CAM and by lost-wax and metal casting techniques.

MethodsOn an upper jaw simulator with KaVo typodont teeth, the left insisor was prepared for single crown. Impression and scans were taken and three copings were manufactured from each group: milled pre-sintered zirconia, milled hot isostatic pressed zirconia, milled lithium disilicate, milled cobalt-chromium, and laser-sintered cobalt-chromium using CAD/CAM technique and cobalt-chromium by the conventional lost-wax and metal casting technique. The internal fit of crowns produced by CAD/CAM technique was compared to crowns produced by metal casting technique. The internal fit was evaluated in buccal-palatinal and in mesio-distal directions using the triple-scan protocol and GOM Inspect software.

ResultsThe internal gaps in mesio-distal and buccal-palatinal directions were statistically smaller for crowns made by conventional lost-wax and metal casting technique compared to crowns produced by CAD/CAM technique (Table 1).

Conclusions
The triple-scan method revealed that single crowns made by lost-wax and metal casting technique had better internal fit than crowns produced by CAD/CAM technique.